Dressing mechanism for grinding wheels



. June 20, 1939.

i A. H. CANDEE ETAL DRESSING MECHANISM FOR GRINDING WHEELS Y Filed June 15, 19-57 3 Sheets-Sheet l V :fm Ry Z l I ,1 1G 44 Allan H Canciee l'mnentora and aeorye 0. Richmond DRESSING MECHANISM FOR GRINDING WHEELS Filed June 15, 1957 s Sheets-Sheet 2 AZLGIIL 'H C nd e Zmvento'rs v j and GeOr;e 0. Richmond f E3 1 F I v .Gflomeg June 20, 1939. A. H. CANDEE' ET AL 2,162,836

- DRESSING MECHANISM FOR GRINDING WHEELS Filed June '15, 1937 3 Sheets-Sheet :s

AZZOZTQHL Cdndee ZSnventor: nd Ge ory'e Richmond (Ittorneg Patented amaze-1939 PATENT OFFICE 2,102,836 nnnssmc nmcnamsu Fon cnmnmc WHEELS Allan H. Oandee and George o; Richmond, Rochester, N. Y., assignors to Gleason .-Works, Rochester. N. Y., a corporation of New York Application June 15, 1937', Serial No. 14 8341 The present invention relates to the dressing of grinding wheels. 1

It is general practice in grinding operations to employ grinding wheels of either cylindrical or 5 conical form because such wheels can be trued or dressed in the simplest possible way, namely, by moving the contact point of a diamond or other suitable dressing tool in a straight line across the active surface of the wheel'- In many operations, however, a straight profiled grinding wheel will notgrind a surface of truly straightprofile. Thus, a cylindrical or a conical wheel will not grind a truly straight profile on a helical. surface such as, for instance, the side of a worm' l5 thread or the cam-relieved side surface of a hob tooth or of a facemill cutter blade. To obtain a truly straight profile in such instances, the grinding wheel used should be dressed to a slightly curved profile. To dress a grinding wheel to a, curved profile, however, a curved guide .or template has heretofore been required and, where the curvature is slight, it is diflicult to make such a guide or template accurately. 'Theusualpractice is to dress the wheel to a straight profile,

5 -(cylindrical or conical) and to accept the resulting slight curvature produced on the work. Often a slight departure from a straight proflleor shape on the ground part is unimportant.

teeth, however, inaccuracies and variations of as.

small as 0.0001" are frequently objectionable and for that reason it has become more-and more desirable to grind worm threadsto a truly straight profile and to grind the relieved side surfaces of gear cutting tools such as hobs and face-mill cutter blades to truly straight profile.

- The primary object of the present invention is to provide a simple, easily constructed and -in-' expensive apparatus for dressing a curved profile on a grinding wheel.

A further object of the invention is to provide apparatus which may readily be adapted to dress grinding wheels to curved profiles of various radii of curvature.

Still another object of the invention is to pro- 5 vide apparatus in which straight guides or templates may be employed to produce a curved proflle on a grinding wheel. A straight guide or template is easy to make accurately and hence the difllculties previously encountered in the making of apparatus for dressing curved profiles on grinding wheels are obviated. l

Other objects of the invention will be apparent hereinafter from the specification. and from the recital of the appended claims. In the drawings:

In gear- 1 Fig. 1 is a side elevation showing a dressing mechanism built according to one of the simplest embodiments of the invention in use for dressing a curved profileupon a grinding wheel;

Fig. 2 is a fragmentary sectional view on the line 22 of Fig. 1;

3 is a more or less diagrammatic view showing the dressing of a grinding wheel'for grinding a worm or hob thread and illustrating the kinematics of the invention; and

. Fig. 4 is a sectional view showing the grinding wheel spindle of a machine forrelief-grinding face-mill .gear cutters and a dressing mechanism constituting one embodiment of this invention for the dressing of the grinding wheel. 4

In dressing apparatus made according to the present invention, a curve is dressed on a grinding wheel by a combined reciprocating and pivotal movement or the dressing tool. The 'dia-. mond or other dressing tool is secured .to a re-- ciprocable carrier that is so controlled by straight I guides as to cause the contact point of the dressing tool to move in a path of known radius of' curvature. V 7

The invention may be embodied in various forms. In one embodiment, the reciprocable dresser carrier is provided with two aTngularly adjustable straight guide-members and the carrier is mounted so that these guide-members engage with and slide on a pair .of spaced guiderollers or pins as the carrier is reciprocated. The guide-members may be inclined to one another at difierent angles to vary the radius of curvature of the curve dressed upon the grinding wheel. In another embodiment of the invention,'the ,dresser carrier'is mounted to reciprocate in a sup about a. hired pivot and the dresser carrier, has

port which is 'pivotally mounted for movement a guide-member secured to it, whichhas a tively fixed part of the dressing mechanism. The

curvature dressed upon the grinding wheel depends, then, on the inclination of the guide-surface or the guide-member.

In any embodiment of the invention, thecurve produced upon the grinding wheel is controlled by'guide-members having straight guide-surfaces which can be or are set out of parallel. Straight guide suriaces are the simplest form to make accurately. Hence, the curve produced upon the grinding wheel may be made very accurately. f Reference will now be had to the drawings for a more detailed description of the invention.

In Figs. 1 and 2, a very simple embodiment of w the invention is illustrated. Here, Ill denotes a head or column in which there is journaled a spindle II that carries the grinding wheel l2 which is to be dressed. The spindle is driven by a pulley l3. The head I8 is shown as provided with an integral arm l4 to which'is secured a block. 15 by meansof a screw I5. The block 15 carries two spaced pins l1 and 18.

The block l5 has a plane outside surface 28. 22 designates a block or carrier in which the diamond or other dressing tool 23 is secured. The carrier 22 has a plane under'face that is adapted to seat and slide upon theplane surface 20 of the block I5; 7

Secured to the under face of the carrier 22 are a, pair of guide-plates 25 and 25 which have straight guide-surfaces or edges 29 and 30, re-

spectively, These plates are secured to the car-.

over the guide block l5 .to reciprocate the dressing tool 23 across the surface of the grinding wheel 12 while holding the guide-surfaces 29 and.

39 firmly in contact with pins 21 and ;28. If the guide-plates 25 and 25 are adjusted so that they are parallel to one another, the contact point of the dresser will then be moved in a straight line, but if the guide-plates 25 and 25 are adjusted so that their guide surfaces are not parallelfthe contact point of the dressing tool 23 will, then, follow a curved path such as that designated at 34 in Fig. 1. The position of the center of curvature can be determined by simple kinematic principles. By varying the inclination of the guide-plates 25 and 25 to one another, the length of the radius of curvature dressed upon the grinding wheel may be varied.

The lines 3| and 32 in-Fig. 1 denote normals through the centers of the guide-pins i1 and [8, respectively, and perpendicular to the straight edges of the guide-plates 25 and-25, respectively.

. The line 33 denotes a line which passes through ent invention for dressing the contact point of the dressing tool and connects that point with the point of intersection of the lines 3| and 32. The center of curvature of the curve .38 dressed upon the grinding wheel is located a proximately 'half-way between this point of intersection and the point of the dressing tool, as may readily be determined.

A wheel su'eh'as shown in I2 111 Fignh dressed to a curved profile may be used in grinding the side suriaces of a worm thread or of the hob teeth 7 and when the wheel is dressed to a slight curvature,-it may be used to correct thecurvature on the ground surface, which occurs when a wheel with truly straight profile is used."

The kinematic principles underlying. the present invention are illustrated in more detail in Fig. 3 which shows a grinding wheel 35 in posi--'- tion to grind one side 35 of the teeth or thread of a hob or worm 31 and which further shows a dressing mechanism made according to the-prescurved profile.

. a dressing-tool 45 which is secured in a'reciprocable carrier 4|. This carrier 41 has a pair of guide-plates 42 and 43 secured to it by screws 44 and 45, respectively. The guide plates 42 and 43 have straight side surfaces 48 and 49, respectively, 7 pins 45 and 41; re-

which slide against the so denotes a line drawn this wheel 35 to a through the center of the guide pin 45 parallel to the straight guide edge 48 of the guide-plate 42. 5| denotes a line drawn through the center of the guide pin 41 parallel to the straight guide-edge 49 of the guideplate 43. 52 is the point of intersection of these two lines 58 and 5|; 54 denotes the circle upon which the point 52 moves as the dresser carrier 4| is reciprocated. 55 is a line drawn through the guide-pin 45 perpendicular to the straight edge 48 of the guide-plate 42, 51 is a line drawn through the center of the guide-pin 41 perpendicular to the straight edge 49 of the guide-plate 43. These two lines intersect in a point 58. 59 is a line connecting the point 58 with the dressing .tool 40. 58' is a line drawn through point 58 perpendicular to the line 59. 5| is a line drawn through the point of the dressing tool and the point 52 of intersection of the lines 58 and 5|. 52 is the point of intersection of the 58 and 5!.

- 63 is a line connecting the points 52 and 5a. 64 is a point on the line 53 equi-distant from the points 52 and 58. 55 is a line connecting the point 54 with the point 52. By the principles of kinematics it is known that the point 55 of intersection of the line 55 with the line 59 is the center of curvature of the path 51 of the-dressing tool 40 as it moves across the grinding wheel,

The center of curvature 55 is seen to be approximately half-way between the diamond point 45 and the intersection point 58 of lines 55 and 51.

In actual practice, the radius of curvature from point 45 to point 55 is usually quite long, say

tools, it is also necessary to grind a helical surface.

Thus in relief-grinding 'fa'ceemill gear cutter blades,-.the relieved side surfaces maybe ground by using a relative helical motion between the grinding wheel and the cutter as eachblade of the cutter rotates under the grinding wheel. When cylindrical or conical forms of grinding wheels are used, a slight curvature is produced on the blade profiles. To correct this, a slight com-' pensating curvature is required on the wheel profile. Fig. 4 shows a dressing mechanism constructed according to the present invention for dressing a' generally cylindrical .form'of grinding wheel with a curved profile so that this grinding wheel may in turn be used to relief-grind side surfaces upon face-mill gear cutter blades which are of straight profile.

denotes the wheel head or support of a standard machine for relief-grinding face-mill ear cutters. V the grinding wheel used in the relief-grinding operation which is to be dressed by the mechanism of the present invention. 13 is a pulley for driving the wheel spindle for 'both and which is secured in a block 11 that is fastened by screws 18 to the head 10. The sleeve or support forms a guide for a bar 89 which reciprocates "is the wheel spindle and '12 in the bore of the sleeve 15. The bar 88 carries a post 8| to which is fastened an arm 82 which carries the dressing tool 84.

The post 8| is adjustable in the bar 88 to adjust the dressing tool'in operative relation with the grinding wheel. For this purpose, the post 8I is made of reduced diameter at its upper end and threaded. It threads into a nut 85 which is secured against axial movement in the bar 88 by means of a thimble 86. The thimble is held inrthe bar by screws 81. The'position of the post 8I and the dressing tool 84 can be adjusted very accurately by means of a micrometer dial 88 which is secured by the set-screw 88 to the nut 85.

The bar 88 is slotted adjacent its rear end to receive a cam or guide-plate 98 which is secured to the bar by screws 9|. vThis guide-plate has a straight guide surface 92 which is inclined to the axis of the bar and of the sleeve I5. The guide-plate 98 is adapted to slide on a roller 83 which is rotatably mounted in the head 18 and which extends through a slot 94 in the sleeve I5 so as to engage. with the straight edge 92 of the guide-plate.

The bar 88 may be reciprocated by any suitable means to pass the dressing tool 84 over the grinding wheel I2. As shown, the bar 88 is connected to the rod 95 of a piston which is adapted to reciprocate in a cylinder 86 that is secured to the sleeve or support 15. The diamond holder may be reciprocated by fluid-pressure.

It is obvious that the grinding wheel-may be dressed to a straight cylindrical form by providing a cam 98 with its guide surface 92 exactly parallel to the axis of the sleeve I5 and by having the height adjustment of cam and roller such that axis of sleeve I5 is parallel to the axis of wheel spindle II. By using a straight guide-surface 92, however, which is somewhat inclined out of, parallel to the axis of sleeve 15, various degrees of curvature may be obtained on the profile of the grinding wheel. of the center of curvature may be known by the .same general method of geometrical construction as explained in detail in connection with Fig. 3.

The line I88 is a line passing through the center of the roller 93 and normal to the straight edge 92 of the guide 88. The line IIII is a line passing through the center of the pivot pin 16 and normal to the bar. The line I82 is a line drawn from the point of the dressing tool 84 to the point of intersection of the lines MI and I88. The center of curvature of the path 98 of the dressing tool is at a point approximately equidistant between this point of intersection of the lines I88 and IM andthe point of the dressing tool.

While various embodiments of the invention have been illustrated, it will be understood that the invention is capable of various further modi fications and the present application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

Having thus described our invention, what we claim is:

i '1. A dressing attachment for a grinding machine comprising a support adapted to be mounted adjacent the wheel which is to be dressed, a

The position slide reciprocable on said support, a dressing tool carried by said slide, spacedcontrol means on said support co'ntrolling the movement of said slide, one of said control means comprising a fixed pivot about which the slide pivots on reciprocation thereof, and the other of said means comprising a templet and a follower, one of which is secured to the'support and the other of which is secured to the slide, said templet having a straight guide surface engaging the follower and which is inclined to the direction of reciprocation of the slide.

2. A dressing attachment for a grinding machine comprising a support adapted to be mounted adjacent the wheel to be dressed, a slide movable on said support, a pair of spaced circular pins mounted on said support, and a pair 01 spaced straight-sided guide members carried by said slide and adapted to slide on said pins as the slide .is reciprocated, said guide members being mounted on the slide to be adjustable angularly relative to one another to incline their guide surfaces out of parallel to each other.

3. A dressing attachment for rotary grinding wheels comprising a support adapted to be mounted adjacent the wheel to /be dressed, aholderpivotally mounted on said support for movement about an axis inclined to'the axis of the wheel, a slide reciprocable rectilinearly on said holder, a dresser, carried by said slide, a roller mounted on said support and a guide member carried by said slide, said guide member having a straight edged guidesurfaee inclined out of parallel tothe direction of reciprocation of the slide and adapted to ride on said roller as the slide is reciprocated to cause said dressing tool to dress a curved Surface on the grinding wheel.

4. Adressing attachment for a grinding machine comprising a support adapted to be mount-' ecl adjacent the wheel which is to be dressed, a slide reciprocable on said support, a dressing tool carried by the slide, a templet and a follower, one of which is secured to the slide and the other of which is secured to said support, means interposed between the dressing tool and the follower and providing a fixed pivot for said slide in its reciprocable movement, said templet having a straight guide surface engaging the follower which is inclined to the direction of movement of said slide.

5. A dressing attachment for a grinding machine comprising a support adapted to be mounted adjacent the wheel to be dressed, a slide re-. ciprocable on said support, apair of straight edged non-parallel guides carried by one of said members and a pair of contact members carried by the other of said members and adapted to ride on said guides, a dressing tool carried by one of said members and means for reciprocating said slide while maintaining the guides and contact members in contact.

6. A dressing attachment for a grinding machine comprising a support adapted to be mounted adjacent the grinding wheel which is to be.

dressed, a slide reciprocable on said support, a

straight-profiled template mounted on the slide with its active surface inclined to the direction of movement of said slide, a follower secured to chine comprising a support adapted to be mounted adjacent the grinding wheel which is to be dressed, a slide reciprocable on said support, a

said template, a dressing tool mounted on said slide, and means forming a fixed pivot for said slide during its reciprocating movement, said means being so located that the slide will pivot,

as it reciprocates, about a fixed axis inclined to 5 the axis of the grinding wheel.

-ALLAN H. CANDEE.

GEORGE O.- RICHMOND. 

